Objectives: 1. Attempt to relate histopathological findings on breast cancer with prognosis, efficacy of therapy, and other diseases. 2. Attempt to define new classifications of breast cancer. 3. Relate histology of breast cancer to various serum tumor markers, such as CEA. Major Findings: Results indicate that patients with breast cancer have a different spectrum of second benign and malignant tumors than female patients with lymphoma. Also found that breast epithelial cells contain a myosin-like protein. Proposed Course: Continue to study and to classify breast cancer cases at NIH and to associate histological observations with clinical and laboratory observations.